.cfg - Configuration files
.ccf - OS/2 Multimedia Viewer configuration file
.pcf - Cisco VPN Client configuration file
.bau - OpenOffice.org configuration file
.sav - Configuration data file
.reg - Registry file for Windows
.plt - Bentley's CAD MicroStation plot driver configuration file
.tsk - Skin file for Windows Mobile
file extension UI - User Interface (Sprint)
File extension UI description:
Probably old file extension or not supported application.
